The present invention is generally directed to the manufacturing of sealed canisters containing an operative substance such as a medicine and a propellant. More particularly, the present invention is directed to testing the integrity of the seal of such canisters, especially canisters utilized in metered dose inhaler systems.
Many types of medicines are provided in fluid form, such as a solution or suspension of particles in a propellant or emulsion, and are adapted for oral inhalation by a patient. As one example, a canister might contain asthma medicine such as fluticasone propionate. During a typical manufacturing process, the canister is sealed with a cap that includes a metering valve. The seal is effected by crimping the valve cap onto the neck of the canister. The canister is then, many times, charged through the valve stem with an aerosol or other propellant.
In order to deliver medicine to the patient, the canister operates in conjunction with an actuator as a system commonly known as a metered dose inhaler (MDI) system. The actuator includes a housing having an open canister-loading end and an open mouthpiece. A nozzle element is disposed within the housing and includes a valve stem-receiving bore communicating with a nozzle orifice. The orifice is aimed toward the mouthpiece. In order to receive a properly metered dosage of medicine from the canister, the patient installs the canister into the actuator through the canister-loading end until the valve stem is fitted into the receiving bore of the nozzle element. With the canister so installed, the opposite end of the canister typically extends to some degree outside the actuator housing. The patient then places the mouthpiece into his or her mouth and pushes downwardly on the exposed canister end. This action causes the canister to displace downwardly with respect to the valve stem, which in turn unseats the valve. Owing to the design of the valve, the design of the nozzle element, and the pressure differential between the interior of the canister and the ambient air, a short burst of precisely metered, atomized medicine is thereby delivered to the patient.
As known to those skilled in the art, the quality of the crimping process by which the valve cap is sealed onto the canister is of utmost criticality. Even a slight defect in the resulting crimp will constitute an improperly sealed valve cap. That is, because of the significant pressure differential between the interior of the canister and the ambient air, the slightest leak will render the canister commercially valueless. By the time the defective canister has been distributed to the patient, most or all of the propellant will have escaped the confines of the canister. As a result, the pressure differential has been eliminated and the canister rendered inoperative.
It would therefore be advantageous to provide a feasible method for identifying and diagnosing problems associated with the canister crimping assemblies employed in MDI production lines. The present invention is provided to address these and other problems associated with the assembly of ends, tops or caps onto open-ended canisters, as well as problems associated with the measurement of height or the determination of levelness for the ends of other types of objects.
The present invention disclosed herein results from an acknowledgment that in order for the valve cap to be crimped onto the canister properly, thus ensuring the integrity of the seal, the valve cap must be accurately aligned onto the canister during the crimping process. It is further acknowledged that accurate alignment, and thus a seal of acceptable quality, can be indicated by measuring the height or the distance of a top surface of the valve cap of an assembled canister with respect to a reference point. By taking several such measurements around a circular line on a flat portion of the top surface of the valve cap, and by comparing those measurements with a predetermined value or range of acceptable values, the levelness of the valve cap can be determined and the integrity of the seal adjudged from the resulting data. The measurements can be taken either by axially rotating the canister and its valve cap with respect to the probing element of a transducer, or by axially rotating the probing element with respect to the valve cap.
The present invention generally provides two approaches to determining the alignment and levelness of the valve cap. In the first approach, a portable, hand-held measuring apparatus is provided for analyzing assembled canisters off-line with regard to the manufacturing process. The first approach is most practicably implemented by employing a micrometer or other transducer that includes a mechanical probe to physically contact the valve cap. In the second approach, a measurement system that includes a measurement station is adapted for integration with the in-line canister assembly process. The second approach is most practicable implemented be employing a non-contacting type of micrometer or transducer. In both approaches, a plurality of standard-sized canisters can be analyzed without changing the set-up or configuration of the apparatus.
In accordance with a first embodiment of the present invention, a measuring apparatus comprises a housing defining an inner chamber therein and a transducer mounted to the housing. The transducer includes a probe that extends into the inner chamber. A mounting platform is disposed within the inner chamber of the housing and is adapted for mounting an object thereon having opposing first and second end surfaces. The measuring apparatus is adapted for relative rotational movement between the mounting platform in the transducer probe so that the probe is caused to contact a portion of the first end surface of the object.
In accordance with another embodiment of the present invention, measuring device comprises a lower section defining a lower interior region, an upper section defining an upper interior region, a mounting platform, and a transducer. The lower section includes a first end surface having an aperture communicating with the lower interior region. The upper section includes first and second end surfaces. The upper section second end surface has an aperture communicating with the upper interior region and extends into the lower interior region of the lower section. The aperture of the upper section second end surface communicates with the lower interior region, and the upper and lower interior regions cooperatively define an inner chamber. The mounting platform is disposed within the inner chamber and is adapted for mounting an object thereon having opposing first and second end surfaces. The transducer is mounted to the upper section and includes a linearly movable probe. The probe extends through the upper interior region and into the inner chamber. The transducer is responsive to a translation of the probe. The apparatus is structurally adapted for relative rotational movement between the mounting platform and the transducer probe so that the probe is caused to contact a portion of the first end surface of the object.
In one of the preferred embodiments according to the present invention, a hollow insert is disposed within the lower section of the measuring device. The insert has an outer lateral surface and an inner lateral surface. When the insert is disposed within the lower section, the outer lateral surface of the insert is adjacent to an inner lateral surface of the lower section. The insert includes a longitudinal slot disposed in parallel with the longitudinal axis and is exposed to the lower interior region of the lower section. A transverse member is attached to an outside lateral surface of the upper section, and extends radially outwardly with respect to the longitudinal axis. The transverse member is slidably disposed in the longitudinal slot.
In another method for determining the levelness of an end surface of an object, a measuring device is provided which comprises a housing defining an inner chamber, a transducer mounted to the housing, and a mounting platform disposed within the inner chamber. The transducer includes a probe extending into the inner chamber. An object including opposed first and second inner surfaces is placed into the inner chamber, and the second end surface of the object is secured onto the mounting platform. The probe is brought into contact with the first end surface of the object. Relative rotational movement is then carried out between the mounting platform and the probe such that the probe travels along a portion of the first end surface of the object.
In another method for determining the levelness of an end surface of an object, a measuring device is provided which comprises a housing including a hollow upper section and a hollow lower section cooperatively defining an inner chamber, a transducer mounted to the housing and including a probe extending into the inner chamber, and a mounting platform disposed within the inner chamber. An object having opposed first and second end surfaces is placed into the inner chamber. The second end surface of the object is secured onto the mounting platform by sliding the upper section into the lower section. The sliding causes a downward displacement of the upper section with respect to the lower section along a central longitudinal axis common to both the upper and lower sections. A distal end of the probe is brought into contact with the first end surface of the object at a point disposed along a circumference of the first end surface. An indication of the levelness of the first end surface of the object is produced by comparing a zero reference point of the probe to a change in displacement of the probe, which displacement change is effected by the contacting of the distal end with the first end surface. The distal end of the probe is then brought into contact with the first end surface at another point disposed along the circumference of the first end surface, and another indication of levelness is produced. This process can be repeated a number of times in order to produce a plurality of indications.
In a further embodiment according to the present invention, a system is provided for detecting an improperly sealed valve of a canister during a canister assembly or filling process. The system comprises a detection station, a conveying device, and a non-contacting measuring device. The conveying device extends through the detection station and includes a movable element. A canister is disposed on the movable element and can be advanced by the movable element through the detection station. The canister includes an open upper canister end sealed by a valve cap having a top surface. The non-contacting measuring device is mounted to the detection station such that it can measure the height of the top surface of the valve cap.
It is therefore an object of the present invention to provide a method and apparatus for measuring the alignment of an end of an object, such as a valve assembled onto a canister.
It is another object of the present invention to provide a method and apparatus for measuring the alignment of a valve assembled onto a plurality of differently sized canisters without having to change the configuration of setup of such apparatus.
It is a further object of the present invention to provide a portable, hand-held apparatus for measuring the alignment of a valve assembled onto a canister.
It is a still further object of the present invention to provide a method and apparatus for measuring the alignment of a valve assembled onto a canister while either axially rotating the canister with respect to a transducer or axially rotating the transducer with respect to the canister.
It is yet another object of the present invention to provide an apparatus for measuring the alignment of a valve assembled onto a canister, wherein the apparatus is integrated with the in-line manufacturing or filling process of the canister.
Some of the objects of the invention having been stated hereinabove, other objects will be evident as the description proceeds, when taken in connection with the accompanying drawings as best described hereinbelow.